PORTLAND, OREGON — A team of researchers at Oregon Health and Science University have successfully performed the first known attempt of creating genetically modified human embryos. <br /> <br />The team used a gene-editing technique called CRISPR, which is capable of finding a target DNA sequence and replacing it with a desired sequence. The technology is theoretically possible to modify the genomes of any living thing on earth. <br /> <br />Once injected, the guide RNA in the CRISPR-Cas9 system seeks out the target DNA before the Cas9 enzyme binds and cuts it. The void in the DNA strand is then filled with the desired sequence. <br /> <br />Researchers in China have previously conducted trials of CRISPR in cancer patients but the results revealed a major problem of the technique: it can cause unwanted mutations other parts of a DNA sequence. This effect is known as mosaicism. <br /> <br />However, the Portland team is confident that it is possible to avoid the errors by injecting CRISPR into the eggs at the same time they were fertilized with sperm. <br /> <br />"It is proof of principle that it can work. They significantly reduced mosaicism. I don't think it's the start of clinical trials yet, but it does take it further than anyone has before," a scientist familiar with the project told MIT Technology Review.
